package com.lliane.LlianeJPFFT;

import java.io.FileOutputStream;
import java.io.IOException;

import android.content.Context;
import android.graphics.Bitmap;
import android.graphics.Canvas;
import android.graphics.Color;
import android.graphics.Paint;
import android.os.Handler;
import android.util.Log;
//Fast Fourrier Transform Class

/*************************************************************************
 * Source : http://www.cs.princeton.edu/introcs/97data/FFT.java.html
 *  Compilation:  javac FFT.java
 *  Execution:    java FFT N
 *  Dependencies: Complex.java
 *
 *  Compute the FFT and inverse FFT of a length N complex sequence.
 *  Bare bones implementation that runs in O(N log N) time. Our goal
 *  is to optimize the clarity of the code, rather than performance.
 *
 *  Limitations
 *  -----------
 *   -  assumes N is a power of 2
 *
 *   -  not the most memory efficient algorithm (because it uses
 *      an object type for representing complex numbers and because
 *      it re-allocates memory for the subarray, instead of doing
 *      in-place or reusing a single temporary array)
 *  
 *************************************************************************/


public class LlianeFFT {	
    // compute the FFT of x[], assuming its length is a power of 2
    public static Complex[] fft(Complex[] x) {
        int N = x.length;

        // base case
        if (N == 1) return new Complex[] { x[0] };

        // radix 2 Cooley-Tukey FFT
        if (N % 2 != 0) { throw new RuntimeException("N is not a power of 2"); }

        // fft of even terms
        Complex[] even = new Complex[N/2];
        for (int k = 0; k < N/2; k++) {
            even[k] = x[2*k];
        }
        Complex[] q = fft(even);

        // fft of odd terms
        Complex[] odd  = even;  // reuse the array
        for (int k = 0; k < N/2; k++) {
            odd[k] = x[2*k + 1];
        }
        Complex[] r = fft(odd);

        // combine
        Complex[] y = new Complex[N];
        for (int k = 0; k < N/2; k++) {
            double kth = -2 * k * Math.PI / N;
            Complex wk = new Complex(Math.cos(kth), Math.sin(kth));
            y[k]       = q[k].plus(wk.times(r[k]));
            y[k + N/2] = q[k].minus(wk.times(r[k]));
        }
        return y;
    }


    // compute the inverse FFT of x[], assuming its length is a power of 2
    public static Complex[] ifft(Complex[] x) {
        int N = x.length;
        Complex[] y = new Complex[N];

        // take conjugate
        for (int i = 0; i < N; i++) {
            y[i] = x[i].conjugate();
        }

        // compute forward FFT
        y = fft(y);

        // take conjugate again
        for (int i = 0; i < N; i++) {
            y[i] = y[i].conjugate();
        }

        // divide by N
        for (int i = 0; i < N; i++) {
            y[i] = y[i].times(1.0 / N);
        }

        return y;

    }

    // compute the circular convolution of x and y
    public static Complex[] cconvolve(Complex[] x, Complex[] y) {

        // should probably pad x and y with 0s so that they have same length
        // and are powers of 2
        if (x.length != y.length) { throw new RuntimeException("Dimensions don't agree"); }

        int N = x.length;

        // compute FFT of each sequence
        Complex[] a = fft(x);
        Complex[] b = fft(y);

        // point-wise multiply
        Complex[] c = new Complex[N];
        for (int i = 0; i < N; i++) {
            c[i] = a[i].times(b[i]);
        }

        // compute inverse FFT
        return ifft(c);
    }


    // compute the linear convolution of x and y
    public static Complex[] convolve(Complex[] x, Complex[] y) {
        Complex ZERO = new Complex(0, 0);

        Complex[] a = new Complex[2*x.length];
        for (int i = 0;        i <   x.length; i++) a[i] = x[i];
        for (int i = x.length; i < 2*x.length; i++) a[i] = ZERO;

        Complex[] b = new Complex[2*y.length];
        for (int i = 0;        i <   y.length; i++) b[i] = y[i];
        for (int i = y.length; i < 2*y.length; i++) b[i] = ZERO;

        return cconvolve(a, b);
    }

    // display an array of Complex numbers to standard output
    public static void show(Complex[] x, String title) {
        Log.d("FFT", title);
        Log.d("FFT", "-------------------");
        for (int i = 0; i < x.length; i++) {
        	Log.d("FFT", x[i].toString());
        }
        Log.d("FFT", "");;
    }


   /*********************************************************************
    *  Test client and sample execution
    *
    *  % java FFT 4
    *  x
    *  -------------------
    *  -0.03480425839330703
    *  0.07910192950176387
    *  0.7233322451735928
    *  0.1659819820667019
    *
    *  y = fft(x)
    *  -------------------
    *  0.9336118983487516
    *  -0.7581365035668999 + 0.08688005256493803i
    *  0.44344407521182005
    *  -0.7581365035668999 - 0.08688005256493803i
    *
    *  z = ifft(y)
    *  -------------------
    *  -0.03480425839330703
    *  0.07910192950176387 + 2.6599344570851287E-18i
    *  0.7233322451735928
    *  0.1659819820667019 - 2.6599344570851287E-18i
    *
    *  c = cconvolve(x, x)
    *  -------------------
    *  0.5506798633981853
    *  0.23461407150576394 - 4.033186818023279E-18i
    *  -0.016542951108772352
    *  0.10288019294318276 + 4.033186818023279E-18i
    *
    *  d = convolve(x, x)
    *  -------------------
    *  0.001211336402308083 - 3.122502256758253E-17i
    *  -0.005506167987577068 - 5.058885073636224E-17i
    *  -0.044092969479563274 + 2.1934338938072244E-18i
    *  0.10288019294318276 - 3.6147323062478115E-17i
    *  0.5494685269958772 + 3.122502256758253E-17i
    *  0.240120239493341 + 4.655566391833896E-17i
    *  0.02755001837079092 - 2.1934338938072244E-18i
    *  4.01805098805014E-17i
    *
    *********************************************************************/
    public static void gen(String classname, String tablename, String[][] src)
	{
		Bitmap bmp = Bitmap.createBitmap(128, 128, Bitmap.Config.ARGB_8888);
		Canvas cvs = new Canvas(bmp);        	
		Paint paint = new Paint();
		int pixels[] = new int [16384];
		Complex pixels_C[] = new Complex [16384];
		paint.setStyle(Paint.Style.FILL);
		paint.setAntiAlias(true);
		paint.setColor(Color.BLACK);
		paint.setTextSize(128);
		paint.setTextAlign(Paint.Align.CENTER);
		Context context;
		String os;
		double myre;
		double myim;
		os = "package com.llianejapan;\n\n";
		os += "public class "+classname+" {\n";
		os += "public static KanjiType[] "+tablename+" = {\n";
		try {
			LlianeJPFFT.o.write(os.getBytes());
		} catch (IOException e) {
			e.printStackTrace();
		}
		for (int i = 0; src[i] != null; i++)
		{
			Log.d(classname, "" + i);
			cvs.drawColor(Color.WHITE);
			cvs.drawText(src[i][1], 64, 110, paint);
			bmp.getPixels(pixels, 0, 128, 0, 0, 128, 128);
			LlianeJPFFT.imgv.setImageBitmap(bmp);
			for (int x = 0; x < 16384; x++)
			{
				if (pixels[x] != Color.BLACK)
				{
					pixels_C[x] = new Complex(1, 0);
				}
				else
					pixels_C[x] = new Complex(0, 0);					
			}
			//Appel a la FFT			
			Complex[] fftr = fft(pixels_C);			
			//Ecriture en output

			os = "new KanjiType(\"" + src[i][0] + "\",\""
			+ src[i][1] + "\"";
			for (int x = 0; x < 10; x++)
			{
				myre = fftr[x].re() * 10000;
				myre = Math.floor(myre + 0.5);
				myre = myre / 10000;
				myim = fftr[x].im() * 10000;
				myim = Math.floor(myim + 0.5);
				myim = myim / 10000;
				
				os += "," + myre;
				os += "," + myim;
			}
			if (src[i + 1] != null)
			  os += "),\n";
			else
			  os += ")\n";
			try {
				LlianeJPFFT.o.write(os.getBytes());
			} catch (IOException e) {
				e.printStackTrace();
			}
		}
		os = "};\n};";
		try {
			LlianeJPFFT.o.write(os.getBytes());
		} catch (IOException e) {
			e.printStackTrace();
		}
	}
	public static void main_test(String[] args) { 
		int N = Integer.parseInt(args[0]);
		Complex[] x = new Complex[N];

		// original data
		for (int i = 0; i < N; i++) {
			x[i] = new Complex(i, 0);
			x[i] = new Complex(-2*Math.random() + 1, 0);
		}
		show(x, "x");

		// FFT of original data
		Complex[] y = fft(x);
		show(y, "y = fft(x)");

		// take inverse FFT
		Complex[] z = ifft(y);
		show(z, "z = ifft(y)");

		// circular convolution of x with itself
		Complex[] c = cconvolve(x, x);
		show(c, "c = cconvolve(x, x)");

		// linear convolution of x with itself
		Complex[] d = convolve(x, x);
		show(d, "d = convolve(x, x)");
	}

}
